String timeTag(void) {
  unsigned long date, time;
  gps.get_datetime(&date, &time);
  String aStr = "T," + String(millis()) + comma + String(date) + comma + String(time);
  return aStr;
}

String gpsString(void) {
  String aStr = "G," + String(millis()) + comma + String(gps.lat) + comma;
  aStr += String(gps.lon) + comma + String(gps.alt);
  return aStr;
}
